Centerless grinding machine



y 1967 J. A. WILSON CENTERLESS GRINDING MACHINE 5 Sheets-Sheet 1 Filed Sept. 4, 1964 ATTORNEYS y 2, 11967 J. A. WILSON 3,316,679

CENTERLESS GRINDING MACHINE Filed Sept. 4, 1964 5 Sheets-Sheet 2 INVENTOR.

JOHN A. WILSON BY ATTORNEYS y 2, 1957 J. A. WILSON CENTERLESS GRINDING MACHINE 5 Sheets-Sheet 3 Filed Sept. 4, 1964 INVENTOR. JOHN A. WILSON fiiww m ATTORNEYS United States Patent 3,316,679 CENTERLESS GRINDING MACHINE John A. Wilson, Cranston, R.I., assignor to Wanskuck Company, a corporation of Rhode Island Filed Sept. 4, 1964, Ser. No. 394,514 4 Claims. (Cl. 51-137) This invention relates to an abrasive belt centerless grinding machine and more particularly to the manner in which the abarasive belt is supported relative to the base of the machine.

Abrasive belt centerless griding machines consist of an endless belt which is supported on a main pressure roller and which is guided over a tension roller that is spaced from the main pressure roll. The roll assembly is suitably supported on a framework which in turn is slidably related to a main base or platform to permit reciprocation of the abrasive belt relative to the work. The material to be ground is generally supported in a suitable manner by the base of the machine for movement across the face of the abrasive. The complete machine also includes a feeding means that generally takes the form of another belt or regulating wheel that is juxtapositioned relative to the main abrasive belt so as to be facing the main abrasive belt. This auxiliary feeding mechanism also serves as a pressure device to urge the work against the main abrasive belt. Machines of this nature are used principally for griding cylindrical surfaces, for example, steel rolls, which rolls are supported vertically with respect to the abrasive wheel from the base of the machine so as to be freely rotatable and which are urged against the abrasive belt by the feed unit pressure assembly. In order to freely change abrasive belts, it is necessary that the main roller and the idler roller be supported in cantilever fashion. Sometimes excessive loads are applied to the abrasive belt and it is therefore apparent that not only must the main roller be of rugged design to accept these loads but also that the loads as transmitted to the base of the machine must be adequately considered. It has been found in the previous constructions that inaccuracies in grinding will result due to a twisting effect that occurs on the abrasive belt support means relative to the base of the machine. It is accordingly a principal object of the present invention to provide an abrasive belt centerless grinding machine which will balance the loads that are impressed upon the belt through the provision of central dovetail ways that accept equally, or at least substantially so, the load that is impressed upon the abrasive belt.

In the drawings:

FIG. 1 is an elevational view showing a grinder constructed in accordance with the invention;

FIG. 2 is a sectional view taken substantially on lines 22 of FIG. 1 with certain parts removed for clarity; and

FIG. 3 is a plan view of the base support for the abrasive belt and feed mechanism.

Referring now to the drawings, generally designates the base of the machine which base is a cast iron struction of rectangular form (see FIG. 3) which has feet 11 from which rise side walls 12 and 13. For support between the side walls 12 and 13, end walls 14 and 15 are provided and at least two internal webs 16 and 17. A top wall 18 generally spans the area between the side and end walls and mounted on this top wall 18 are two sets of ways generally designated 20 and 21. These ways are of usual form and include the ground surfaces upon which mating parts are adapted to rest and include the usual gib such as 22 (see FIG. 2). Located immediately below the top wall 18 of the base is a drain pan 23 upon which coolant liquid is adapted to fall through apertures such as at 24 and thence flow by gravity into a collection tank 25.

Mounted on the sets of ways 20 is a feed unit generally designated 28 which essentially consists of a pair of mechanically driven rolls 29, 30 around which is trained a belt B. Motor 35 and drive coupling 36 supply controlled rotation to rolls 29, '30 in a manner well known. The rolls '29, 30 are mounted in such a fashion that they may rock in a vertical plane by reason of their sole suspension from a mounting plate 31 onto a drive member 32 and of course may be moved towards and away from the work by virtue of the usual feed screw 33 and a hand wheel such as 34, which mechanical arrangement moves the entire assemblage on the ways 20.

Mounted on the ways 21 in a generally L shaped carriage which is broadly designated 40 and which includes a base portion 41 having a dovetail lower portion as at 42 for association with the ways 21. Rising from the base portion 41 is a vertical portion 43. A shaft 44 passes through this vertical member and is journaled therein, the shaft supporting at one end a plurality of sheaves 45 and at the other end a contact wheel 46. Motor means 47 are suitably mounted on the top of the vertical portion 43 by the use of auxiliary brackets such as 48 that extend over the contact wheel 46 and the motor is provided with a plurality of sheaves 43 which connect through a plurality of belts 50 to the sheaves 45, thus driving the contact wheel 46. It is sometimes desirable because of the loads exerted on the contact wheel 46 to provide an outer bearing support for the shaft 44 upon which the wheel is received. To this end a plate-like bracket 52 is suitably supported from the vertical member 43 by means not shown and carries at one end thereof a bearing 53. A hydraulic cylinder 55 is also mounted on the member 43 and has a piston rod 56 which supports a yoke 57, the yoke in turn rotatably supporting an idler roll 60. Passing over the main contact roll 46 and the idler roll 60 is a belt 62 which has abrasive grains imbedded thereon to serve as a cutting means and it will be apparent that the idler roll 6tls position relative to the roll 46 may be adjusted by the hydraulic cylinder to provide proper belt tension by means well known to those skilled in the art.

It will further be noted that so far as the description has proceeded, that the contact wheel 46 is related to the ways 21 in such a fashion that the center line of the contact wheel 46 passes through the center line of the ways 21. This is particularly evident by examining FIG. 2 of the drawings and by providing this type of structure with the particular arrangement of the contact wheel in an overhanging relationship relative to the ways, it will be apparent that substantially equal forces will be exerted on each way and will prevent any twisting effect of the frame which supports the contact wheel relative to the ways. It is found in some instances that pressures as exerted against the contact wheel may be in many instances suflicient to actually cock the contact wheel slide 42 relative to the ways, which result is not obtained with the arrangement of parts as shown herein.

In operation, there is placed on a base plate 38 a suitable work support such as 39 (see FIG. 1) which in turn will readily support a cylindrical member such as W between the abrasive belt 62 and the belt that passes over the feed unit. Pressure is principally supplied by the pressure exerted against the work by the feed unit, the feed unit operating to traverse the work relative to the belt 62 by merely angularly relating the moving belt 62 to the longitudinal extent of the Work and thus effecting not only rotation of the work but also a feed thereof at a rate dependent upon the degree of angularity imparted to the belt that passes over the rolls 29 and 30 as related to the axis of the work.

I claim:

1. A centerless grinder comprising a bed, a pair of ways on said bed, a carriage slidably mounted on said ways, a driven contact wheel journaled in said carriage centrally of said ways, an abrasive belt embracing said contact wheel, a work rest mounted on said bed, a pressure means supported above said bed, said pressure means comprising a driven endless belt also being centrally located transverse of said ways whereby pressure exerted on a workpiece by the pressure means against the cutter is equally resisted by each way.

2. A grinder as in claim 1 wherein said carriage comprises a base portion having interengaging means with said ways and a vertical portion rising from said base portion at one edge thereof, the said contact wheel being journaled in said vertical portion and axially located so as to lie centrally of said base portion.

3. A grinder as in claim 2 wherein an outer bearing for said contact wheel is supported from said vertical portion.

4. A centerless grinder as in claim 3 wherein said outer bearing for said contact wheel is supported from said vertical portion and within the orbit of said belt.

References Cited by the Examiner UNITED STATES PATENTS 1,179,999 4/ 1916 Blevney. 1,777,607 10/1930 Ekholm 51103 2,341,442 2/1944 Hulbert 51l41 X ROBERT C. RIORDON, Primary Examiner.

D. G. KELLEY, Assistant Examiner. 

1. A CENTERLESS GRINDER COMPRISING A BED, A PAIR OF WAYS ON SAID BED, A CARRIAGE SLIDABLY MOUNTED ON SAID WAYS, A DRIVEN CONTACT WHEEL JOURNALED IN SAID CARRIAGE CENTRALLY OF SAID WAYS, AN ABRASIVE BELT EMBRACING SAID CONTACT WHEEL, A WORK REST MOUNTED ON SAID BED, A PRESSURE MEANS SUPPORTED ABOVE SAID BED, SAID PRESSURE MEANS COMPRISING A DRIVEN ENDLESS BELT ALSO BEING CENTRALL LOCATED TRANSVERSE OF SAID WAYS WHEREBY PRESSURE EXERTED ON A WORKPIECE BY THE PRESSURE MEANS AGAINST THE CUTTER IS EQUALLY RESISTED BY EACH WAY. 